Mr. Darwin's long-standing and well-earned scientific
eminence probably renders him indifferent to that social notoriety which passes
by the name of success; but if the calm spirit of the philosopher have not yet
wholly superseded the ambition and the vanity of the carnal man within him,
he must be well satisfied with the results of his venture in publishing the
"Origin of Species." Overflowing the narrow bounds of purely scientific circles,
the "species question" divides with Italy and the Volunteers the attention of
general society. Everybody has read Mr. Darwin's book, or, at least, has given
an opinion upon its merits or demerits; pietists, whether lay or ecclesiastic,
decry it with the mild railing which sounds so charitable; bigots denounce it
with ignorant invective; old ladies of both sexes consider it a decidedly
dangerous book, and even savants, who have no better mud to throw, quote antiquated
writers to show that its author is no better than an ape himself; while every
philosophical thinker hails it as a veritable Whitworth gun in the armoury of
liberalism; and all competent naturalists and physiologists, whatever their
opinions as to the ultimate fate of the doctrines put forth, acknowledge that
the work in which they are embodied is a solid contribution to knowledge and
inaugurates a new epoch in natural history.

Nor has the discussion of the subject been restrained within
the limits of conversation. When the public is eager and interested, reviewers
must minister to its wants; and the genuine littérateur is too
much in the habit of acquiring his knowledge from the book he judges as the
Abyssinian is said to provide himself with steaks from the ox which carries
him to be withheld from criticism of a profound scientific work by the mere
want of the requisite preliminary scientific acquirement; while, on the other
hand, the men of science who wish well to the new views, no less than those
who dispute their validity, have naturally sought opportunities of expressing
their opinions. Hence it is not surprising that almost all the critical journals
have noticed Mr. Darwin's work at greater or less length; and so many disquisitions,
of every degree of excellence, from the poor product of ignorance, too often
stimulated by prejudice, to the fair and

thoughtful essay of the candid
student of Nature, have appeared, that it seems an almost hopeless task to attempt
to say anything new upon the question.

But it may be doubted if the knowledge and acumen of prejudged
scientific opponents, and the subtlety of orthodox special pleaders, have yet
exerted their full force in mystifying the real issues of the great controversy
which has been set afoot, and whose end is hardly likely to be seen by this
generation; so that, at this eleventh hour, and even failing anything new, it
may be useful to state afresh that which is true, and to put the fundamental
positions advocated by Mr. Darwin in such a form that they may be grasped by
those whose special studies lie in other directions. And the adoption of this
course may be the more advisable, because, notwithstanding its great deserts,
and indeed partly on account of them, the "Origin of Species" is by no means
an easy book to read if by reading is implied the full comprehension of an author's
meaning.

We do not speak jestingly in saying that it is Mr. Darwin's
misfortune to know more about the question he has taken up than any man living.
Personally and practically exercised in zoology, in minute anatomy, in geology;
a student of geographical distribution, not on maps and in museums only, but
by long voyages and laborious collection; having largely advanced each of these
branches of science, and having spent many years in gathering and sifting
materials for his present work, the store of accurately registered facts upon
which the author of the "Origin of Species" is able to draw at will is prodigious.

But this very superabundance of matter must have been embarrassing
to a writer who, for the present, can only put forward an abstract of his views;
and thence it arises, perhaps, that notwithstanding the clearness of the style,
those who attempt fairly to digest the book find much of it a sort of intellectual
pemmican a mass of facts crushed and pounded into shape, rather than held together
by the ordinary medium of an obvious logical bond; due attention will, without
doubt, discover this bond, but it is often hard to find.

Again, from sheer want of room, much has to be taken for granted
which might readily enough be proved; and hence, while the adept, who can supply
the missing links in the evidence from his own knowledge, discovers fresh proof
of the singular thoroughness with which all difficulties have been considered
and all unjustifiable suppositions avoided, at every reperusal of Mr. Darwin's
pregnant paragraphs, the novice in biology is apt to complain of the frequency
of what he fancies is gratuitous assumption.

Thus while it may be doubted if, for some years, any one is
likely to be competent to pronounce judgment on all the issues

raised by Mr.
Darwin, there is assuredly abundant room for him, who, assuming the humbler,
though perhaps as useful, office of an interpreter between the "Origin of Species"
and the public, contents himself with endeavouring to point out the nature of
the problems which it discusses; to distinguish between the ascertained facts
and the theoretical views which it contains; and finally, to show the extent
to which the explanation it offers satisfies the requirements of scientific
logic. At any rate, it is this office which we purpose to undertake in the following
pages.

It may be safely assumed that our readers have a general conception
of the nature of the objects to which the word "species" is applied; but it
has, perhaps, occurred to a few, even to those who are naturalists ex professo, to reflect, that, as commonly employed, the term has a double sense and denotes
two very different orders of relations. When we call a group of animals, or
of plants, a species, we may imply thereby, either that all these animals or
plants have some common peculiarity of form or structure; or, we may mean that
they possess some common functional character. That part of biological science
which deals with form and structure is called Morphology that which concerns
itself with function, Physiology so that we may conveniently speak of these
two senses, or aspects, of "species" the one as morphological, the other as
physiological. Regarded from the former point of view, a species is nothing
more than a kind of animal or plant, which is distinctly definable from all
others, by certain constant, and not merely sexual, morphological peculiarities.
Thus horses form a species, because the group of animals to which that name
is applied is distinguished from all others in the world by the following constantly
associated characters. They have1, A vertebral column; 2, Mammæ; 3, A
placental embryo; 4, Four legs; 5, A single well-developed toe in each foot
provided with a hoof; 6, A bushy tail; and 7, Callosities on the inner sides
of both the fore and the hind legs. The asses, again, form a distinct species,
because, with the same characters, as far as the fifth in the above list, all
asses have tufted tails, and have callosities only on the inner side of the
fore-legs. If animals were discovered having the general characters of the horse,
but sometimes with callosities only on the fore-legs, and more or less tufted
tails; or animals having the general characters of the ass, but with more or
less bushy tails, and sometimes with callosities on both pairs of legs, besides
being intermediate in other respects the two species would have to be merged
into one. They could no longer be regarded as morphologically distinct species,
for they would not be distinctly definable one from the other.

to be, we confidently appeal to all practical naturalists, whether zoologists,
botanists, or palæontologists, to say if, in the vast majority of cases,
they know, or mean to affirm anything more of the group of animals or plants
they so denominate than what has just been stated. Even the most decided advocates
of the received doctrines respecting species admit this.

"I apprehend," says Professor Owen,* "that few naturalists nowadays, in describing and proposing a name for what
they call 'a new species,' use that term to signify what was meant by
it twenty or thirty years ago; that is, an originally distinct creation, maintaining
its primitive distinction by obstructive generative peculiarities. The proposer
of the new species now intends to state no more than he actually knows; as,
for example, that the differences on which he founds the specific character
are constant in individuals of both sexes, so far as observation has reached;
and that they are not due to domestication or to artificially superinduced external
circumstances, or to any outward influence within his cognizance; that the species
is wild, or is such as it appears by Nature."

If we consider, in fact, that by far the largest proportion
of recorded existing species are known only by the study of their skins, or
bones, or other lifeless exuviæ; that we are acquainted with none, or
next to none, of their physiological peculiarities, beyond those which can be
deduced from their structure, or are open to cursory observation; and that we
cannot hope to learn more of any of those extinct forms of life which now constitute
no inconsiderable proportion of the known Flora and Fauna of the world:
it is obvious that the definitions of these species can be only of a purely
structural, or morphological, character. It is probable that naturalists would
have avoided much confusion of ideas if they had more frequently borne the necessary
limitations of our knowledge in mind. But while it may safely be admitted that
we are acquainted with only the morphological characters of the vast majority
of species the functional or physiological, peculiarities of a few have been
carefully investigated, and the result of that study forms a large and most
interesting portion of the physiology of reproduction.

The student of Nature wonders the more and is astonished the
less, the more conversant he becomes with her operations; but of all the perennial
miracles she offers to his inspection, perhaps the most worthy of admiration
is the development of a plant or of an animal from its embryo. Examine the recently
laid egg of some common animal, such as a salamander or newt. It is a minute
spheroid in which the best microscope will reveal nothing but a structureless

* On the Osteology
of the Chimpanzees and Orangs. Transactions of the Zoological Society, 1858.

sac, enclosing a glairy fluid, holding granules in suspension. But strange possibilities lie dormant in that semi-fluid globule. Let a moderate
supply of warmth reach its watery cradle, and the plastic matter undergoes changes so rapid, yet so steady and purpose-like in their succession, that one
can only compare them to those operated by a skilled modeller upon a formless
lump of clay. As with an invisible trowel, the mass is divided and subdivided
into smaller and smaller portions, until it is reduced to an aggregation of
granules not too large to build withal the finest fabrics of the nascent organism.
And, then, it is as if a delicate finger traced out the line to be occupied
by the spinal column, and moulded the contour of the body; pinching up the head
at one end, the tail at the other, and fashioning flank and limb into due salamandrine
proportions, in so artistic a way, that, after watching the process hour by
hour, one is almost involuntarily possessed by the notion, that some more subtle
aid to vision than an achromatic, would show the hidden artist, with his plan
before him, striving with skilful manipulation to perfect his work.

As life advances, and the young amphibian ranges the waters,
the terror of his insect contemporaries, not only are the nutritious particles
supplied by its prey, by the addition of which to its frame, growth takes place,
laid down, each in its proper spot, and in such due proportion to the rest,
as to reproduce the form, the colour, and the size, characteristic of the parental
stock; but even the wonderful powers of reproducing lost parts possessed by
these animals are controlled by the same governing tendency. Cut off the legs,
the tail, the jaws, separately or all together, and, as Spallanzani showed
long ago, these parts not only grow again, but the redintegrated limb is formed
on the same type as those which were lost. The new jaw, or leg, is a newt's,
and never by any accident more like that of a frog. What is true of the newt
is true of every animal and of every plant; the acorn tends to build itself
up again into a woodland giant such as that from whose twig it fell; the spore
of the humblest lichen reproduces the green or brown incrustation which gave
it birth; and at the other end of the scale of life, the child that resembled
neither the paternal nor the maternal side of the house would be regarded as
a kind of monster.

So that the one end to which, in all living beings, the formative
impulse is tending the one scheme which the Archæus of the old speculators
strives to carry out, seems to be to mould the offspring into the likeness of
the parent. It is the first great law of reproduction, that the offspring tends
to resemble its parent or parents, more closely than anything else.

Science will some day show us how this law is a necessary consequence
of the more general laws which govern matter; but, for

the present, more can
hardly be said than that it appears to be in harmony with them. We know that
the phænomena of vitality are not something apart from other physical
phænomena, but one with them; and matter and force are the two names
of the one artist who fashions the living as well as the lifeless. Hence living
bodies should obey the same great laws as other matter nor, throughout Nature,
is there a law of wider application than this, that a body impelled by two forces
takes the direction of their resultant. But living bodies may be regarded as
nothing but extremely complex bundles of forces held in a mass of matter, as
the complex forces of a magnet are held in the steel by its coercive force;
and, since the differences of sex are comparatively slight, or, in other words,
the sum of the forces in each has a very similar tendency, their resultant,
the offspring, may reasonably be expected to deviate but little from a course
parallel to either, or to both.

Represent the reason of the law to ourselves by what physical
metaphor or analogy we will, however, the great matter is to apprehend its existence
and the importance of the consequences deducible from it. For things which are
like to the same are like to one another; and if; in a great series of generations,
every offspring is like its parent, it follows that all the offspring and all
the parents must be like one another; and that, given an original parental stock,
with the opportunity of undisturbed multiplication, the law in question necessitates
the production, in course of time, of an indefinitely large group, the whole
of the members of which are at once very similar and are blood relations,
having descended from the same parent, or pair of parents. The proof that all
the members of any given group of animals, or plants, had thus descended, would
be ordinarily considered sufficient to entitle them to the rank of physiological
species, for most physiologists consider species to be definable as "the offspring
of a single primitive stock."

But though it is quite true that all those groups we call species
may, according to the known laws of reproduction, have descended from a single
stock, and though it is very likely they really have done so, yet this conclusion
rests on deduction and can hardly hope to establish itself upon a basis of observation.
And the primitiveness of the supposed single stock, which, after all, is the
essential part of the matter, is not only a hypothesis, but one which has not
a shadow of foundation, if by "primitive" be meant "independent of any other
living being." A scientific definition, of which an unwarrantable hypothesis
forms an essential part, carries its condemnation within itself; but, even supposing
such a definition were, in form, tenable, the physiologist who should attempt
to apply it in Nature would soon find himself involved in great, if not inextricable,
difficulties. As we have said, it is indubitable that offspring tend to resemble the parental organism,

but it is equally true that the similarity
attained never amounts to identity either in form or in structure. There
is always a certain amount of deviation, not only from the precise characters
of a single parent, but when, as in most animals and many plants, the sexes
are lodged in distinct individuals, from an exact mean between the two parents.
And indeed, on general principles, this slight deviation seems as intelligible
as the general similarity, if we reflect how complex the co-operating "bundles
of forces" are, and how improbable it is that, in any case, their true resultant
shall coincide with any mean between the more obvious characters of the two
parents. Whatever be its cause, however, the co-existence of this tendency to
minor variation with the tendency to general similarity, is of vast importance
in its bearing on the question of the origin of species.

As a general rule, the extent to which an offspring differs
from its parent is slight enough; but, occasionally, the amount of difference
is much more strongly marked, and then the divergent offspring receives the
name of a Variety. Multitudes, of what there is every reason to believe are
such varieties, are known, but the origin of very few has been accurately recorded,
and of these we will select two as more especially illustrative of the main
features of variation. The first of them is that of the "Ancon" or "Otter" sheep,
of which a careful account is given by Colonel David Humphreys, F.R.S., in a
letter to Sir Joseph Banks, published in the "Philosophical Transactions"
for 1813. It appears that one Seth Wright, the proprietor of a farm on the banks
of the Charles River, in Massachusetts, possessed a flock of fifteen ewes and
a ram of the ordinary kind. In the year 1791, one of the ewes presented her
owner with a male lamb, differing, for no assignable reason, from its parents
by a proportionally long body and short bandy legs, whence it was unable to
emulate its relatives in those sportive leaps over the neighbours' fences, in
which they were in the habit of indulging, much to the good farmer's vexation.

The second case is that detailed by a no less unexceptionable
authority than Réaumur, in his "Art de faire éclore les Poulets."
A Maltese couple, named Kelleia, whose hands and feet were constructed upon
the ordinary human model, had born to them a son, Gratio, who possessed six
perfectly movable fingers on each hand, and six toes, not quite so well formed,
on each foot. No cause could be assigned for the appearance of this unusual
variety of the human species.

Two circumstances are well worthy of remark in both these cases.
In each, the variety appears to have arisen in full force, and, as it were, per saltum; a wide and definite difference appealing, at once, between
the Ancon ram and the ordi-

nary sheep; between the six-fingered and six-toed
Gratio Kelleia and ordinary men. In neither case is it possible to point
out any obvious reason for the appearance of the variety. Doubtless there were
determining causes for these as for all other phænomena; but they do not
appear, and we can be tolerably certain that what are ordinarily understood
as changes in physical conditions, as in climate, in food, or the like, did
not take place and had nothing to do with the matter. It was no case of what
is commonly called adaptation to circumstances; but, to use a conveniently erroneous
phrase, the variations arose spontaneously. The fruitless search after final
causes leads their pursuers a long way; but even those hardy teleologists, who
are ready to break through all the laws of physics in chase of their favourite
will-o'-the-wisp, may be puzzled to discover what purpose could be attained
by the stunted legs of Seth Wright's ram or the hexadactyle members of Gratio
Kelleia.

Varieties then arise we know not why; and it is more than probable
that the majority of varieties have arisen in this "spontaneous" manner, though
we are, of course, far from denying that they may be traced, in some cases,
to distinct external influences; which are assuredly competent to alter the
character of the tegumentary covering, to change colour, to increase or diminish
the size of muscles, to modify constitution, and, among plants, to give rise
to the metamorphosis of stamens into petals, and so forth. But however they
may have arisen, what especially interests us at present is, to remark
that, once in existence, many varieties obey the fundamental law of reproduction
that like tends to produce like; and their offspring exemplify it by tending
to exhibit the same deviation from the parental stock as themselves. Indeed,
there seems to be, in many instances, a prepotent influence about a newly-arisen
variety which gives it what one may call an unfair advantage over the normal
descendants from the same stock. This is strikingly exemplified by the case
of Gratio Kelleia, who married a woman with the ordinary pentadactyle extremities,
and had by her four children, Salvator, George, André, and Marie. Of
these children Salvator, the eldest boy, had six fingers and six toes, like
his father; the second and third, also boys, had five fingers and five toes,
like their mother, though the hands and feet of George were slightly deformed.
The last, a girl, had five fingers and five toes, but the thumbs were slightly
deformed. The variety thus reproduced itself purely in the eldest, while the
normal type reproduced itself purely in the third, and almost purely in the
second and last: so that it would seem, at first, as if the normal type were
more powerful than the variety. But all these children grew up and intermarried
with normal wives and husband, and then, note what took place: Salvator had
four children, three of

whom exhibited the hexadactyle members of their grandfather
and father, while the youngest had the pentadactyle limbs of the mother
and grandmother; so that here, notwithstanding a double pentadactyle dilution
of the blood, the hexadactyle variety had the best of it. The same pre-potency
of the variety was still more markedly exemplified in the progeny of two of
the other children, Marie and George. Marie (whose thumbs only were deformed)
gave birth to a boy with six toes, and three other normally formed children;
but George, who was not quite so pure a pentadactyle, begot, first, two girls,
each of whom had six fingers and toes; then a girl with six fingers on each
hand and six toes on the right foot, but only five toes on the left; and lastly,
a boy with only five fingers and toes. In these instances, therefore, the variety,
as it were, leaped over one generation to reproduce itself in full force in
the next. Finally, the purely pentadactyle André was the father of many
children, not one of whom departed from the normal parental type.

If a variation which approaches the nature of a monstrosity
can strive thus forcibly to reproduce itself, it is not wonderful that less
aberrant modifications should tend to be preserved even more strongly; and the
history of the Ancon sheep is, in this respect, particularly instructive. With
the "cuteness" characteristic of their nation, the neighbours of the Massachusetts
farmer imagined it would be an excellent thing if all his sheep were imbued
with the stay-at-home tendencies enforced by Nature upon the newly-arrived
ram; and they advised Wright to kill the old patriarch of his fold, and install
the Ancon ram in his place. The result justified their sagacious anticipations,
and coincided very nearly with what occurred to the progeny of Gratio Kelleia.
The young lambs were almost always either pure Ancons, or pure ordinary sheep.* But when sufficient Ancon sheep were obtained to interbreed with one another,
it was found that the offspring was always pure Ancon. Colonel Humphreys, in
fact, states that he was acquainted with only "one questionable case of a contrary
nature." Here, then, is a remarkable and well-established instance, not only
of a very distinct race being established per saltum, but of that race

* Colonel Humphreys'
statements are exceedingly explicit on this point: "When an Ancon ewe is impregnated
by a common ram, the increase resembles wholly either the ewe or the ram. The
increase of the common ewe impregnated by an Ancon ram follows entirely the
one or the other, without blending any of the distinguishing and essential peculiarities
of both. Frequent instances have happened where common ewes have had twins by
Ancon rams, when one exhibited the complete marks and features of the ewe, the
other of the ram. The contrast has been rendered singularly striking, when one
short-legged and one long-legged lamb, produced at a birth, have been seen sucking
the dam at the same time." Philosophical Transactions, 1813, Pt. I. pp.
89, 90.

breeding "true" at once, and showing no mixed forms, even when crossed with
another breed.

By taking care to select Ancons of both sexes, for breeding
from, it thus became easy to establish an extremely well-marked race; so peculiar
that, even when herded with other sheep, it was noted that the Ancons kept
together. And there is every reason to believe that the existence of this breed
might have been indefinitely protracted; but the introduction of the Merino
sheep, which were not only very superior to the Ancons in wool and meat, but
quite as quiet and orderly, led to the complete neglect of the new breed, so
that, in 1813, Colonel Humphreys found it difficult to obtain the specimen,
the skeleton of which was presented to Sir Joseph Banks. We believe that, for
many years, no remnant of it has existed in the United States.

Gratio Kelleia was not the progenitor of a race of six-fingered
men, as Seth Wright's ram became a nation of Ancon sheep, though the tendency
of the variety to perpetuate itself appears to have been fully as strong in
the one case as in the other. And the reason of the difference is not far to
seek. Seth Wright took care not to weaken the Ancon blood by matching his Ancon
ewes with any but males of the same variety, while Gratio Kelleia's sons were
too far removed from the patriarchal times to intermarry with their sisters;
and his grand-children seem not to have been attracted by their six-fingered
cousins. In other words, in the one example a race was produced, because, for
several generations, care was taken to select both parents of the breeding
stock from animals exhibiting a tendency to vary in the same direction;
while, in the other, no race was evolved, because no such selection was exercised.
A race is a propagated variety; and as, by the laws of reproduction, offspring
tend to assume the parental forms, they will be more likely to propagate a variation
exhibited by both parents than that possessed by only one.

There is no organ of the body of an animal which may not, and
does not, occasionally, vary more or less from the normal type; and there is
no variation which may not be transmitted and which, if selectively transmitted,
may not become the foundation of a race. This great truth, sometimes forgotten
by philosophers, has long been familiar to practical agriculturists and breeders;
and upon it rest all the methods of improving the breeds of domestic animals,
which, for the last century, have been followed with so much success in England.
Colour, form, size, texture of hair or wool, proportions of various parts, strength
or weakness of constitution, tendency to fatten or to remain lean, to give much
or little milk, speed, strength, temper, intelligence, special instincts; there
is not one of these characters

whose transmission is not an every-day
occurrence within the experience of cattle-breeders, stock-farmers, horse-dealers,
and dog and poultry fanciers. Nay, it is only the other day that an eminent
physiologist, Dr. Brown-Séquard, communicated to the Royal Society his
discovery that epilepsy, artificially produced in guinea-pigs, by a means
which he has discovered, is transmitted to their offspring.

But a race, once produced, is no more a fixed and immutable
entity than the stock whence it sprang; variations arise among its members,
and as these variations are transmitted like any others, new races may be developed
out of the pre-existing one ad infinitum, or, at least, within any limit
at present determined. Given sufficient time and sufficiently careful selection,
and the multitude of races which may arise from a common stock is as astonishing
as are the extreme structural differences which they may present. A remarkable
example of this is to be found in the rock-pigeon, which Mr. Darwin has, in
our opinion, satisfactorily demonstrated to be the progenitor of all our domestic
pigeons, of which there are certainly more than a hundred well-marked races.
The most noteworthy of these races are, the four great stocks known to the "fancy"
as tumblers, pouters, carriers, and fantails; birds which not only differ most
singularly in size, colour, and habits, but in the form of the beak and of the
skull: in the proportions of the beak to the skull; in the number of tail-feathers;
in the absolute and relative size of the feet; in the presence or absence of
the uropygial gland; in the number of vertebræ in the back; in short,
in precisely those characters in which the genera and species of birds
differ from one another.

And it is most remarkable and instructive to observe, that
none of these races can be shown to have been originated by the action of changes
in what are commonly called external circumstances, upon the wild rock-pigeon.
On the contrary, from time immemorial pigeon-fanciers have had essentially similar
methods of treating their pets, which have been housed, fed, protected and cared
for in much the same way in all pigeonries. In fact, there is no case better
adapted than that of the pigeons to refute the doctrine which one sees put forth
on high authority, that "no other characters than those founded on the development
of bone for the attachment of muscles" are capable of variation. In precise
contradiction of this hasty assertion, Mr. Darwin's researches prove that the
skeleton of the wings in domestic pigeons has hardly varied at all from that
of the wild type; while, on the other hand, it is in exactly those respects,
such as the relative length of the beak and skull, the number of the vertebræ,
and the number of the tail-feathers,

in which muscular exertion can have no
important influence, that the utmost amount of variation has taken place.

We have said that the following out of the properties exhibited
by physiological species would lead us into difficulties, and at this point
they begin to be obvious; for if, as the result of spontaneous variation
and of selective breeding, the progeny of a common stock may become separated
into groups distinguished from one another by constant, not sexual, morphological
characters, it is clear that the physiological definition of species is likely
to clash with the morphological definition. No one would hesitate to describe
the pouter and the tumbler as distinct species, if they were found fossil, or
if their skins and skeletons were imported, as those of exotic wild birds commonly
are and without doubt, if considered alone, they are good and distinct morphological
species. On the other hand, they are not physiological species, for they are
descended from a common stock, the rock-pigeon.

Under these circumstances, as it is admitted on all sides that
races occur in Nature, how are we to know whether any apparently distinct animals
are really of different physiological species, or not, seeing that the amount
of morphological difference is no safe guide? Is there any test of a physiological
species? The usual answer of physiologists is in the affirmative. It is said
that such a test is to be found in the phænomena of hybridisation in the
results of crossing races, as compared with the results of crossing species.

So far as the evidence goes at present, individuals, of what
are certainly known to be mere races produced by selection, however distinct
they may appear to be, not only breed freely together, but the offspring
of such crossed races are perfectly fertile with one another. Thus, the spaniel
and the greyhound, the dray-horse and the Arab, the pouter and the tumbler,
breed together with perfect freedom, and their mongrels, if matched with other
mongrels of the same kind, are equally fertile.

On the other hand, there can be no doubt that the individuals
of many natural species are either absolutely infertile if crossed with individuals
of other species, or, if they give rise to hybrid offspring, the hybrids so
produced are infertile when paired together. The horse and the ass, for instance,
if so crossed, give rise to the mule, and there is no certain evidence of offspring
ever having been produced by a male and female mule. The unions of the rock-pigeon
and the ring-pigeon appear to be equally barren of result. Here, then, says
the physiologist, we have a means of distinguishing any two true species from
any two varieties. If a male and a female, selected from each group, produce
offspring, and that offspring is fertile with others pro-

duced in the same way,
the groups are races and not species. If, on the other hand, no result ensues,
or if the offspring are infertile with others produced in the same way, they
are true physiological species. The test would be an admirable one, if, in the
first place, it were always practicable to apply it, and if, in the second,
it always yielded results susceptible of a definite interpretation. Unfortunately, in the great majority of cases, this touchstone for species is wholly inapplicable.

The constitution of many wild animals is so altered by confinement
that they will not breed even with their own females, so that the negative results
obtained from crosses are of no value; and the antipathy of wild animals of
different species for one another, or even of wild and tame members of the same
species, is ordinarily so great, that it is hopeless to look for such unions
in Nature. The hermaphrodism of most plants, the difficulty in the way of insuring
the absence of their own or the proper working of other pollen, are obstacles
of no less magnitude in applying the test to them. And, in both animals and
plants, is superadded the further difficulty, that experiments must be continued
over a long time for the purpose of ascertaining the fertility of the mongrel
or hybrid progeny, as well as of the first crosses from which they spring.

Not only do these great practical difficulties lie in the way
of applying the hybridisation test, but even when this oracle can be questioned,
its replies are sometimes as doubtful as those of Delphi. For example, cases
are cited by Mr. Darwin, of plants which are more fertile with the pollen of
another species than with their own; and there are others, such as certain Fuci, the male element of which will fertilise the ovule of a plant of distinct species,
while the males of the latter species are ineffective with the females
of the first. So that, in the last-named instance, a physiologist, who should
cross the two species in one way, would decide that they were true species;
while another, who should cross them in the reverse way, would, with equal justice,
according to the rule, pronounce them to be mere races. Several plants, which
there is great reason to believe are mere varieties, are almost sterile when
crossed; while both animals and plants, which have always been regarded by naturalists
as of distinct species, turn out, when the test is applied, to be perfectly
fertile. Again, the sterility or fertility of crosses seems to bear no relation
to the structural resemblances or differences of the members of any two groups.

Mr. Darwin has discussed this question with singular ability
and circumspection, and his conclusions are summed up as follows, at page 276
of his work:

species, and their hybrids, are very generally, but not universally, sterile.
The sterility is of all degrees, and is often so slight that the two most careful
experimentalists who have ever lived have come to diametrically opposite conclusions
in ranking forms by this test. The sterility is innately variable in individuals
of the same species, and is eminently susceptible of favourable and unfavourable
conditions. The degree of sterility does not strictly follow systematic affinity,
but is governed by several curious and complex laws. It is generally different
and sometimes widely different, in reciprocal crosses between the same
two species. It is not always equal in degree in a first cross, and in the hybrid
produced from this cross.

"In the same manner as in grafting trees, the capacity of one
species or variety to take on another is incidental on generally unknown differences
in their vegetative systems; so in crossing, the greater or less facility of
one species to unite with another is incidental on unknown differences in their
reproductive systems. There is no more reason to think that species have been
specially endowed with various degrees of sterility to prevent them crossing
and breeding in Nature, than to think that trees have been specially endowed
with various and somewhat analogous degrees of difficulty in being grafted together,
in order to prevent them becoming inarched in our forests.

"The sterility of first crosses between pure species, which
have their reproductive systems perfect, seems to depend on several circumstances;
in some cases largely on the early death of the embryo. The sterility of hybrids
which have their reproductive systems imperfect, and which have had this system
and their whole organisation disturbed by being compounded of two distinct species,
seems closely allied to that sterility which so frequently affects pure species
when their natural conditions of life have been disturbed. This view is supported
by a parallelism of another kind: namely, that the crossing of forms, only slightly
different, is favourable to the vigour and fertility of the offspring; and that
slight changes in the conditions of life are apparently favourable to the vigour
and fertility of all organic beings. It is not surprising that the degree of
difficulty in uniting two species, and the degree of sterility of their hybrid
offspring, should generally correspond, though due to distinct causes; for both
depend on the amount of difference of some kind between the species which are
crossed. Nor is it surprising that the facility of effecting a first cross,
the fertility of hybrids produced from it, and the capacity of being grafted
together though this latter capacity evidently depends on widely different circumstances should
all run to a certain extent parallel with the systematic affinity of the forms
which are subjected to experiment; for systematic affinity attempts to
express all kinds of resemblance between all species.

"First crosses between forms known to be varieties, or sufficiently
alike to be considered as varieties, and their mongrel offspring, are very generally,
but not quite universally, fertile. Nor is this nearly general and perfect fertility
surprising, when we remember how liable we are to argue in a circle with respect
to varieties in a state of Nature; and when we remember that the greater number
of varieties have been

produced under domestication by the selection of mere
external differences, and not of differences in the reproductive system. In
all other respects, excluding fertility, there is a close general resemblance
between hybrids and mongrels." (pp. 276-8).

We fully agree with the general tenor of this weighty passage;
but forcible as are these arguments, and little as the value of fertility or
infertility as a test of species may be, it must not be forgotten that the really
important fact, so far as the inquiry into the origin of species goes, is, that
there are such things in Nature as groups of animals and of plants, the members
of which are incapable of fertile union with those of other groups; and that
there are such things as hybrids, which are absolutely sterile when crossed
with other hybrids. For, if such phænomena as these were exhibited by
only two of those assemblages of living objects, to which the name of species
(whether it be used in its physiological or in its morphological sense) is given,
it would have to be accounted for by any theory of the origin of species, and
every theory which could not account for it would be, so far, imperfect.

Up to this point, we have been dealing with matters of
fact, and the statements which we have laid before the reader would, to the
best of our knowledge, be admitted to contain a fair exposition of what is at
present known respecting the essential properties of species, by all who have
studied the question. And whatever may be his theoretical views, no naturalist
will probably be disposed to demur to the following summary of that exposition:

Living beings, whether animals or plants, are divisible into
multitudes of distinctly definable kinds, which are morphological species. They
are also divisible into groups of individuals, which breed freely together,
tending to reproduce their like, and are physiological species. Normally resembling
their parents, the offspring of members of these species are still liable to
vary; and the variation may be perpetuated by selection, as a race, which race,
in many cases, presents all the characteristics of a morphological species.
But it is not as yet proved that a race ever exhibits, when crossed with another
race of the same species, those phænomena of hybridisation which are exhibited
by many species when crossed with other species. On the other hand, not only
is it not proved that all species give rise to hybrids infertile inter se, but there is much reason to believe that, in crossing, species exhibit every
gradation from perfect sterility to perfect fertility.

Such are the most essential characteristics of species.
Even were man not one of them a member of the same system and subject to the
same laws the question of their origin, their causal connexion, that is, with
the other phænomena of the uni-

verse, must have attracted his attention,
as soon as his intelligence had raised itself above the level of his daily wants.

Indeed history relates that such was the case, and has embalmed
for us the speculations upon the origin of living beings, which were among the
earliest products of the dawning intellectual activity of man. In those early
days positive knowledge was not to be had, but the craving after it needed,
at all hazards, to be satisfied, and according to the country, or the turn of
thought, of the speculator, the suggestion that all living things arose from
the mud of the Nile, from a primeval egg, or from some more anthropomorphic
agency, afforded a sufficient resting-place for his curiosity. The myths of
Paganism are as dead as Osiris or Zeus, and the man who should revive them,
in opposition to the knowledge of our time, would be justly laughed to scorn;
but the coeval imaginations current among the rude inhabitants of Palestine,
recorded by writers whose very name and age are admitted by every scholar to
be unknown, have unfortunately not yet shared their fate, but, even at this
day, are regarded by nine-tenths of the civilised world as the authoritative
standard of fact and the criterion of the justice of scientific conclusions,
in all that relates to the origin of things, and, among them, of species. In
this nineteenth century, as at the dawn of modern physical science, the cosmogony
of the semi-barbarous Hebrew is the incubus of the philosopher and the opprobrium
of the orthodox. Who shall number the patient and earnest seekers after truth,
from the days of Galileo until now, whose lives have been embittered and their
good name blasted by the mistaken zeal of Bibliolaters? Who shall count the
host of weaker men whose sense of truth has been destroyed in the effort to
harmonise impossibilities whose life has been wasted in the attempt to force
the generous new wine of Science into the old bottles of Judaism, compelled
by the outcry of the same strong party?

It is true that if philosophers have suffered, their cause
has been amply avenged. Extinguished theologians lie about the cradle of every
science as the strangled snakes beside that of Hercules; and history records
that whenever science and orthodoxy have been fairly opposed, the latter has
been forced to retire from the lists, bleeding and crushed if not annihilated;
scotched, if not slain. But orthodoxy is the Bourbon of the world of thought.
It learns not, neither can it forget; and though, at present, bewildered and
afraid to move, it is as willing as ever to insist that the first chapter of
Genesis contains the beginning and the end of sound science; and to visit, with
such petty thunderbolts as its half-paralysed hands can hurl, those who
refuse to degrade Nature to the level of primitive Judaism.

dencies.
With eyes fixed on the noble goal to which "per aspera et ardua" they tend,
they may, now and then, be stirred to momentary wrath by the unnecessary obstacles
with which the ignorant, or the malicious, encumber, if they cannot bar, the
difficult path; but why should their souls be deeply vexed? The majesty of Fact
is on their side, and the elemental forces of Nature are working for them. Not
a star comes to the meridian at its calculated time but testifies to the justice
of their methods their beliefs are "one with the falling rain and with the growing
corn." By doubt they are established, and open inquiry is their bosom friend.
Such men have no fear of traditions however venerable, and no respect for them
when they become mischievous and obstructive; but they have better than mere
antiquarian business in hand, and if dogmas, which ought to be fossil but are
not, are not forced upon their notice, they are too happy to treat them as non-existent.

The hypotheses respecting the origin of species which profess
to stand upon a scientific basis, and, as such, alone demand serious attention,
are of two kinds. The one, the "special creation" hypothesis, presumes
every species to have originated from one or more stocks, these not being the
result of the modification of any other form of living matter or arising by
natural agencies but being produced, as such, by a supernatural creative act.

The other, the so-called "transmutation" hypothesis, considers
that all existing species are the result of the modification of pre-existing
species, and those of their predecessors, by agencies similar to those which
at the present day produce varieties and races, and therefore in an altogether
natural way; and it is a probable, though not a necessary consequence of this
hypothesis, that all living beings have arisen from a single stock. With respect
to the origin of this primitive stock, or stocks, the doctrine of the origin
of species is obviously not necessarily concerned. The transmutation hypothesis,
for example, is perfectly consistent either with the conception of a special
creation of the primitive germ, or with the supposition of its having arisen,
as a modification of inorganic matter, by natural causes.

The doctrine of special creation owes its existence very largely
to the supposed necessity of making science accord with the Hebrew cosmogony;
but it is curious to observe that, as the doctrine is at present maintained
by men of science, it is as hopelessly inconsistent with the Hebrew view as
any other hypothesis.

If there be any result which has come more clearly out
of geological investigation than another, it is, that the vast series of extinct
animals and plants is not divisible, as it was once supposed to be, into distinct
groups, separated by sharply-marked boundaries.

There are no great gulfs between
epochs and formations no successive periods marked by the appearance of plants,
of water animals, and of land animals, en masse. Every year adds to the
list of links between what the older geologists supposed to be widely separated
epochs: witness the crags linking the drift with older tertiaries; the Maestricht
beds linking the tertiaries with the chalk; the St. Cassian beds exhibiting
an abundant fauna of mixed mesozoic and palæozoic types, in rocks of an
epoch once supposed to be eminently poor in life; witness, lastly, the incessant
disputes as to whether a given stratum shall be reckoned devonian or carboniferous,
silurian or devonian, cambrian or silurian.

This truth is further illustrated in a most interesting manner
by the impartial and highly competent testimony of M. Pictet, from whose calculations
of what percentage of the genera of animals, existing in any formation, lived
during the preceding formation, it results that in no case is the proportion
less than one-third, or 33 per cent. It is the triassic formation, or
the commencement of the mesozoic epoch, which has received the smallest inheritance
from preceding ages. The other formations not uncommonly exhibit 60, 80,
or even 94 per cent. of genera in common with those whose remains are imbedded
in their predecessor. Not only is this true, but the subdivisions of each formation
exhibit new species characteristic of, and found only in, them; and, in many
cases, as in the lias for example, the separate beds of these subdivisions are
distinguished by well-marked and peculiar forms of life. A section, a hundred
feet thick, will exhibit, at different heights, a dozen species of ammonite,
none of which passes beyond its particular zone of limestone, or clay, into
the zone below it or into that above it; so that those who adopt the doctrine
of special creation must be prepared to admit, that at intervals of time, corresponding
with the thickness of these beds, the Creator thought fit to interfere with
the natural course of events for the purpose of making a new ammonite. It is
not easy to transplant oneself into the frame of mind of those who can accept
such a conclusion as this, on any evidence short of absolute demonstration;
and it is difficult to see what is to be gained by so doing, since, as we have
said, it is obvious that such a view of the origin of living beings is utterly
opposed to the Hebrew cosmogony. Deserving no aid from the powerful arm of Bibliolatry,
then, does the received form of the hypothesis of special creation derive any
support from science or sound logic? Assuredly not much. The arguments
brought forward in its favour all take one form: If species were not supernaturally
created, we cannot understand the facts x or y, or z; we
cannot understand the structure of animals or plants, unless we suppose they
were contrived

for special ends; we cannot understand the structure of the eye,
except by supposing it to have been made to see with; we cannot understand instincts,
unless we suppose animals to have been miraculously endowed with them.

As a question of dialectics, it must be admitted that this
sort of reasoning is not very formidable to those who are not to be frightened
by consequences. It is an argumentum ad ignorantiam take this explanation
or be ignorant. But suppose we prefer to admit our ignorance rather than adopt
a hypothesis at variance with all the teachings of Nature? Or, suppose for a
moment we admit the explanation, and then seriously ask ourselves how much the
wiser are we; what does the explanation explain? Is it any more than a grandiloquent
way of announcing the fact, that we really know nothing about the matter? A
phænomenon is explained when it is shown to be a case of some general
law of Nature; but the supernatural interposition of the Creator can, by the
nature of the case, exemplify no law, and if species have really arisen in this
way, it is absurd to attempt to discuss their origin.

Or, lastly, let us ask ourselves whether any amount of
evidence which the nature of our faculties permits us to attain, can justify
us in asserting that any phænomenon is out of the reach of natural causation.
To this end it is obviously necessary that we should know all the consequences
to which all possible combinations, continued through unlimited time, can give
rise. If we knew these, and found none competent to originate species, we should
have good ground for denying their origin by natural causation. Till we know
them, any hypothesis is better than one which involves us in such miserable
presumption.

But the hypothesis of special creation is not only a mere specious
mask for our ignorance; its existence in Biology marks the youth and imperfection
of the science. For what is the history of every science but the history of
the elimination of the notion of creative, or other interferences, with the
natural order of the phænomena which are the subject-matter of that science?
When Astronomy was young "the morning stars sang together for joy," and the
planets were guided in their courses by celestial hands. Now, the harmony of
the stars has resolved itself into gravitation according to the inverse squares
of the distances, and the orbits of the planets are deducible from the laws
of the forces which allow a schoolboy's stone to break a window. The lightning
was the angel of the Lord; but it has pleased Providence, in these modern
times, that science should make it the humble messenger of man, and we know
that every flash that shimmers about the horizon on a summer's evening is determined
by ascertainable conditions, and that its direction and brightness

might, if
our knowledge of these were great enough, have been calculated.

The solvency of great mercantile companies rests on the validity
of the laws which have been ascertained to govern the seeming irregularity of
that human life which the moralist bewails as the most uncertain of things;
plague, pestilence, and famine are admitted, by all but fools, to be the natural
result of causes for the most part fully within human control, and not the unavoidable
tortures inflicted by wrathful Omnipotence upon His helpless handiwork.

Harmonious order governing eternally continuous progress the
web and woof of matter and force interweaving by slow degrees, without a broken
thread, that veil which lies between us and the Infinite that universe which
alone we know or can know; such is the picture which science draws of the world,
and in proportion as any part of that picture is in unison with the rest, so
may we feel sure that it is rightly painted. Shall Biology alone remain out
of harmony with her sister sciences?

Such arguments against the hypothesis of the direct creation
of species as these are plainly enough deducible from general considerations;
but there are, in addition, phænomena exhibited by species themselves,
and yet not so much a part of their very essence as to have required earlier
mention, which are in the highest degree perplexing, if we adopt the popularly
accepted hypothesis. Such are the facts of distribution in space and in time;
the singular phænomena brought to light by the study of development; the
structural relations of species upon which our systems of classification are
founded; the great doctrines of philosophical anatomy, such as that of homology,
or of the community of structural plan exhibited by large groups of species
differing very widely in their habits and functions.

The species of animals which inhabit the sea on opposite sides
of the isthmus of Panama are wholly distinct the animals and plants which inhabit islands are commonly distinct from those
of the neighbouring mainlands, and yet have a similarity of aspect. The mammals
of the latest tertiary epoch in the Old and New Worlds belong to the same genera,
or family groups, as those which now inhabit the same great geographical area.
The crocodilian reptiles which existed in the earliest secondary epoch were
similar in general structure to those now living, but exhibit slight differences
in their vertebræ, nasal passages, and one or two other points. The guinea-pig
has teeth which are shed before it is born, and hence can never subserve the
masticatory purpose for which they seem contrived, and, in like manner, the
female dugong has tusks which never cut the gum. All the members of the same
great group run through similar conditions in their

development, and all their
parts, in the adult state, are arranged according to the same plan. Man is more
like a gorilla than a gorilla is like a lemur. Such are a few, taken at random,
among the multitudes of similar facts which modern research has established;
but when the student seeks for an explanation of them from the supporters of
the received hypothesis of the origin of species, the reply he receives is,
in substance, of Oriental simplicity and brevity"Mashallah! it so pleases God!"
There are different species on opposite sides of the isthmus of Panama, because
they were created different on the two sides. The pliocene mammals are like
the existing ones, because such was the plan of creation; and we find rudimental
organs and similarity of plan, because it has pleased the Creator to set before
Himself a "divine exemplar or archetype," and to copy it in His works; and somewhat
ill, those who hold this view imply, in some of them. That such verbal hocus-pocus
should be received as science will one day be regarded as evidence of the low
state of intelligence in the nineteenth century, just as we amuse ourselves
with the phraseology about Nature's abhorrence of a vacuum, wherewith Torricellis
compatriots were satisfied to explain the rise of water in a pump. And be it
recollected that this sort of satisfaction works not only negative but positive
ill, by discouraging inquiry, and so depriving man of the usufruct of one of
the most fertile fields of his great patrimony, Nature.

The objections to the doctrine of the origin of species by
special creation which have been detailed, must have occurred, with more or
less force, to the mind of every one who has seriously and independently considered
the subject. It is therefore no wonder that, from time to time, this hypothesis
should have been met by counter hypotheses, all as well, and some better founded
than itself; and it is curious to remark that the inventors of the opposing
views seem to have been led into them as much by the knowledge of geology, as
by their acquaintance with biology. In fact, when the mind has once admitted
the conception of the gradual production of the present physical state of our
globe, by natural causes operating through long ages of time, it will be little
disposed to allow that living beings have made their appearance in another way,
and the speculations of De Maillet and his successors are the natural complement
of Scilla's demonstration of the true nature of fossils.

A contemporary of Newton and of Leibnitz, sharing therefore
in the intellectual activity of the remarkable age which witnessed the birth
of modern physical science, Benoît de Maillet spent a long life as a consular
agent of the French Government in various Mediterranean ports. For sixteen years,
in fact, he held the office of Consul-General in Egypt, and the wonderful phænomena

offered by the valley of the Nile appear to have strongly impressed his mind,
to have directed his attention to all facts of a similar order which came within
his observation, and to have led him to speculate on the origin of the present
condition of our globe and of its inhabitants. But, with all his ardour for
science, De Maillet seems to have hesitated to publish views which, notwithstanding
the ingenious attempts to reconcile them with the Hebrew hypothesis contained
in the preface to "Telliamed," were hardly likely to be received with favour
by his contemporaries.

But a short time had elapsed since more than one of the great
anatomists and physicists of the Italian school had paid dearly for their endeavours
to dissipate some of the prevalent errors; and their illustrious pupil, Harvey,
the founder of modern physiology, had not fared so well, in a country less oppressed
by the benumbing influences of theology, as to tempt any man to follow his example.
Probably not uninfluenced by these considerations, his Catholic majesty's Consul-General
for Egypt kept his theories to himself throughout a long life, for "Telliamed,"
the only scientific work which is known to have proceeded from his pen, was
not printed till 1735, when its author had reached the ripe age of seventy-nine;
and though De Maillet lived three years longer, his book was not given to the
world before 1748. Even then it was anonymous to those who were not in the secret
of the anagrammatic character of its title; and the preface and dedication are
so worded as, in case of necessity, to give the printer a fair chance of falling
back on the excuse that the work was intended for a mere jeu d'esprit.

The speculations of the suppositious Indian sage, though quite
as sound as those of many a "Mosaic Geology," which sells exceedingly well,
have no great value if we consider them by the light of modern science. The
waters are supposed to have originally covered the whole globe; to have deposited
the rocky masses which compose its mountains by processes comparable to those
which are now forming mud, sand, and shingle; and then to have gradually lowered
their level, leaving the spoils of their animal and vegetable inhabitants embedded
in the strata. As the dry land appeared, certain of the aquatic animals are
supposed to have taken to it, and to have become gradually adapted to terrestrial
and aerial modes of existence. But if we regard the general tenor and style
of the reasoning in relation to the state of knowledge of the day, two
circumstances appear very well worthy of remark. The first, that De Maillet
had a notion of the modifiability of living forms (though without any precise
information on the subject), and how such modifiability might account for the
origin of species; the second, that he very clearly apprehended

the great modern
geological doctrine, so strongly insisted upon by Hutton, and so ably and comprehensively
expounded by Lyell, that we must look to existing causes for the explanation
of past geological events. Indeed, the following passage of the preface, in
which De Maillet is supposed to speak of the Indian philosopher Telliamed, his alter ego, might have been written by the most philosophical uniformitarian
of the present day:

But De Maillet was before his age, and as could hardly fail
to happen to one who speculated on a zoological and botanical question before
Linnæus, and on a physiological problem before Haller, he fell into great
errors here and there; and hence, perhaps, the general neglect of his work.
Robinet's speculations are rather behind, than in advance of, those of De Maillet;
and though Linnæus may have played with the hypothesis of transmutation,
it obtained no serious support until Lamarck adopted it, and advocated it with
great ability in his "Philosophie Zoologique."

Impelled towards the hypothesis of the transmutation of species,
partly by his general cosmological and geological views; partly by the conception
of a graduated, though irregularly branching, scale of being, which had arisen
out of his profound study of plants and of the lower forms of animal life, Lamarck,
whose general line of thought often closely resembles that of De Maillet, made
a great advance upon the crude and merely speculative manner in which that writer
deals with the question of the origin of living beings, by endeavouring to find
physical causes competent to effect that change of one species into another,
which De Maillet had only supposed to occur. And Lamarck conceived that he had
found in Nature such causes, amply sufficient for the purpose in view.
It is a physiological fact, he says, that organs are increased in size by action,
atrophied by inaction; it is another

physiological fact that modifications produced
are transmissible to offspring. Change the actions of an animal, therefore,
and you will change its structure, by increasing the development of the parts
newly brought into use and by the diminution of those less used; but by altering
the circumstances which surround it you will alter its actions, and hence, in
the long run, change of circumstance must produce change of organisation. All
the species of animals, therefore, are, in Lamarck's view, the result of the
indirect action of changes of circumstance, upon those primitive germs which
he considered to have originally arisen, by spontaneous generation, within the
waters of the globe. It is curious, however, that Lamarck should insist so strongly* as he has done, that circumstances never in any degree directly modify the form
or the organisation of animals, but only operate by changing their wants and
consequently their actions; for he thereby brings upon himself the obvious question,
How, then, do plants, which cannot be said to have wants or actions, become
modified? To this he replies, that they are modified by the changes in their
nutritive processes, which are effected by changing circumstances; and it does
not seem to have occurred to him that such changes might be as well supposed
to take place among animals.

When we have said that Lamarck felt that mere speculation was
not the way to arrive at the origin of species, but that it was necessary, in
order to the establishment of any sound theory on the subject, to discover by
observation or otherwise, some vera causa, competent to give rise to
them; that he affirmed the true order of classification to coincide with the
order of their development one from another; that he insisted on the necessity
of allowing sufficient time, very strongly; and that all the varieties of instinct
and reason were traced back by him to the same cause as that which has given
rise to species, we have enumerated his chief contributions to the advance of
the question. On the other hand, from his ignorance of any power in Nature competent
to modify the structure of animals, except the development of parts, or atrophy
of them, in consequence of a change of needs, Lamarck was led to attach infinitely
greater weight than it deserves to this agency, and the absurdities into which
he was led have met with deserved condemnation. Of the struggle for existence,
on which, as we shall see, Mr. Darwin lays such great stress, he had no conception;
indeed, he doubts whether there really are such things as extinct species, unless
they be such large animals as may have met their death at the hands of
man; and so little does he dream of there being any other destructive causes
at work, that, in discussing

the possible existence of fossil shells, he asks,
"Pourquoi d'ailleurs seroient-ils perdues dès que l'homme n'a pu opérer
leur destruction?" ("Phil. Zool.," vol. i. p. 77.) Of the influence of selection
Lamarck has as little notion, and he makes no use of the wonderful phænomena
which are exhibited by domesticated animals, and illustrate its powers. The
vast influence of Cuvier was employed against the Lamarckian views, and, as
the untenability of some of his conclusions was easily shown, his doctrines
sank under the opprobrium of scientific, as well as of theological, heterodoxy.
Nor have the efforts made of late years to revive them tended to re-establish
their credit in the minds of sound thinkers acquainted with the facts of the
case; indeed it may be doubted whether Lamarck has not suffered more from his
friends than from his foes.

Two years ago, in fact, though we venture to question if even
the strongest supporters of the special creation hypothesis had not, now and
then, an uneasy consciousness that all was not right, their position seemed
more impregnable than ever, if not by its own inherent strength, at any rate
by the obvious failure of all the attempts which had been made to carry it.
On the other hand, however much the few, who thought deeply on the question
of species, might be repelled by the generally received dogmas, they saw no
way of escaping from them save by the adoption of suppositions so little justified
by experiment or by observation as to be at least equally distasteful.

The choice lay between two absurdities and a middle condition
of uneasy scepticism; which last, however unpleasant and unsatisfactory, was
obviously the only justifiable state of mind under the circumstances.

Such being the general ferment in the minds of naturalists,
it is no wonder that they mustered strong in the rooms of the Linnæan
Society, on the 1st of July of the year 1858, to hear two papers by authors
living on opposite sides of the globe, working out their results independently,
and yet professing to have discovered one and the same solution of all the problems
connected with species. The one of these authors was an able naturalist, Mr.
Wallace, who had been employed for some years in studying the productions of
the islands of the Indian Archipelago, and who had forwarded a memoir embodying
his views to Mr. Darwin, for communication to the Linnæan Society. On
perusing the essay, Mr. Darwin was not a little surprised to find that it embodied
some of the leading ideas of a great work which he had been preparing for twenty
years, and parts of which, containing a development of the very same views, had been perused by his private friends fifteen or sixteen years before.
Perplexed in what manner to do full justice both to his friend and to himself,
Mr. Darwin placed the matter in the hands of Dr. Hooker and Sir Charles

Lyell,
by whose advice he communicated a brief abstract of his own views to the Linnæan
Society, at the same time that Mr. Wallace's paper was read. Of that abstract,
the work on the "Origin of Species" is an enlargement; but a complete statement
of Mr. Darwin's doctrine is looked for in the large and well-illustrated work
which he is said to be preparing for publication.

The Darwinian hypothesis has the merit of being eminently simple
and comprehensible in principle, and its essential positions may be stated in
a very few words: all species have been produced by the development of varieties
from common stocks; by the conversion of these, first into permanent races and
then into new species, by the process of natural selection, which process
is essentially identical with that artificial selection by which man has originated
the races of domestic animals the struggle for existence taking the place
of man, and exerting, in the case of natural selection, that selective action
which he performs in artificial selection.

The evidence brought forward by Mr. Darwin in support of his
hypothesis is of three kinds. First, he endeavours to prove that species
may be originated by selection; secondly, he attempts to show that natural causes
are competent to exert selection; and thirdly, he tries to prove that the most
remarkable and apparently anomalous phænomena exhibited by the distribution,
development, and mutual relations of species, can be shown to be deducible from
the general doctrine of their origin, which he propounds, combined with the
known facts of geological change; and that, even if all these phænomena
are not at present explicable by it, none are necessarily inconsistent with
it.

There cannot be a doubt that the method of inquiry which Mr.
Darwin has adopted is not only rigorously in accordance with the canons of scientific
logic, but that it is the only adequate method. Critics exclusively trained
in classics or in mathematics, who have never determined a scientific fact in
their lives by induction from experiment or observation, prate learnedly about
Mr. Darwin's method, which is not inductive enough, not Baconian enough, forsooth,
for them. But even if practical acquaintance with the process of scientific
investigation is denied them, they may learn, by the perusal of Mr. Mill's admirable
chapter "On the Deductive Method," that there are multitudes of scientific inquiries
in which the method of pure induction helps the investigator but a very little
way.

"The mode of investigation," (says Mr. Mill) "which from
the proved inapplicability of direct methods of observation and experiment,
remains to us as the main source of the knowledge we possess, or can acquire,
respecting the conditions and laws of recurrence of the more

complex phænomena,
is called, in its most general expression, the deductive method, and consists
of three operations: the first, one of direct induction; the second, of ratiocination;
and the third, of verification."

Now, the conditions which have determined the existence of
species are not only exceedingly complex, but, so far as the great majority
of them are concerned, are necessarily beyond our cognisance. But what Mr. Darwin
has attempted to do is in exact accordance with the rule laid down by Mr. Mill;
he has endeavoured to determine certain great facts inductively, by observation
and experiment; he has then reasoned from the data thus furnished; and lastly,
he has tested the validity of his ratiocination by comparing his deductions
with the observed facts of Nature. Inductively, Mr. Darwin endeavours to prove
that species arise in a given way. Deductively, he desires to show that, if
they arise in that way, the facts of distribution, development, classification,
&c., may be accounted for, i.e. may be deduced from their mode of
origin, combined with admitted changes in physical geography and climate, during
an indefinite period. And this explanation, or coincidence of observed with
deduced facts, is, so far as it extends, a verification of the Darwinian view.

There is no fault to be found with Mr. Darwin's method,
then; but it is another question whether he has fulfilled all the conditions
imposed by that method. Is it satisfactorily proved, in fact, that species may
be originated by selection? that there is such a thing as natural selection?
that none of the phænomena exhibited by species are inconsistent with
the origin of species in this way? If these questions can be answered in the
affirmative, Mr. Darwin's view steps out of the rank of hypotheses into those
of proved theories; but, so long as the evidence at present adduced falls short
of enforcing that affirmation, so long, to our minds, must the new doctrine
be content to remain among the former an extremely valuable, and in the highest
degree probable, doctrine, indeed the only extant hypothesis which is worth
anything in a scientific point of view; but still a hypothesis, and not yet
the theory of species.

After much consideration, and with assuredly no bias against
Mr. Darwin's views, it is our clear conviction that, as the evidence stands,
it is not absolutely proven that a group of animals, having all the characters
exhibited by species in Nature, has ever been originated by selection, whether
artificial or natural. Groups having the morphological character of species distinct
and permanent races in fact have been so produced over and over again; but there
is no positive evidence, at present, that any group of animals has, by variation
and selective breeding, given rise to

another group which was, even in
the least degree, infertile with the first. Mr. Darwin is perfectly aware of
this weak point, and brings forward a multitude of ingenious and important arguments
to diminish the force of the objection. We admit the value of these arguments
to their fullest extent; nay, we will go so far as to express our belief that
experiments, conducted by a skilful physiologist, would very probably obtain
the desired production of mutually more or less infertile breeds from a common
stock, in a comparatively few years; but still, as the case stands at present,
this "little rift within the lute" is not to be disguised nor overlooked.

In the remainder of Mr. Darwin's argument our own private ingenuity
has not hitherto enabled us to pick holes of any great importance; and judging
by what we hear and read, other adventurers in the same field do not seem to
have been much more fortunate. It has been urged, for instance, that in his
chapters on the struggle for existence and on natural selection, Mr. Darwin
does not so much prove that natural selection does occur, as that it must occur;
but, in fact, no other sort of demonstration is attainable. A race does not
attract our attention in Nature until it has, in all probability, existed for
a considerable time, and then it is too late to inquire into the conditions
of its origin. Again, it is said that there is no real analogy between the selection
which takes place under domestication, by human influence, and any operation
which can be effected by Nature, for man interferes intelligently. Reduced to
its elements, this argument implies that an effect produced with trouble by
an intelligent agent must, a fortiori, be more troublesome, if not impossible,
to an unintelligent agent. Even putting aside the question whether Nature, acting
as she does according to definite and invariable laws, can be rightly called
an unintelligent agent, such a position as this is wholly untenable. Mix salt
and sand, and it shall puzzle the wisest of men, with his mere natural appliances,
to separate all the grains of sand from all the grains of salt; but a shower
of rain will effect the same object in ten minutes. And so, while man may find
it tax all his intelligence to separate any variety which arises, and to breed
selectively from it, the destructive agencies incessantly at work in Nature,
if they find one variety to be more soluble in circumstances than the other,
will inevitably, in the long run, eliminate it.

A frequent and a just objection to the Lamarckian hypothesis
of the transmutation of species is based upon the absence of transitional forms
between many species. But against the Darwinian hypothesis this argument has
no force. Indeed, one of the most valuable and suggestive parts of Mr. Darwin's
work is that in which he proves, that the frequent absence of transitions is
a necessary consequence of his doctrine, and that the stock whence

two or more
species have sprung, need in no respect be intermediate between these species.
If any two species have arisen from a common stock in the same way as the carrier
and the pouter, say, have arisen from the rock-pigeon, then the common stock
of these two species need be no more intermediate between the two than the rock-pigeon
is between the carrier and pouter. Clearly appreciate the force of this analogy,
and all the arguments against the origin of species by selection, based on the
absence of transitional forms, fall to the ground. And Mr. Darwin's position
might, we think, have been even stronger than it is if he had not embarrassed
himself with the aphorism, "Natura non facit saltum," which turns up
so often in his pages. We believe, as we have said above, that Nature does make
jumps now and then, and a recognition of the fact is of no small importance
in disposing of many minor objections to the doctrine of transmutation.

But we must pause. The discussion of Mr. Darwin's arguments
in detail would lead us far beyond the limits within which we proposed, at starting,
to confine this article. Our object has been attained if we have given an intelligible,
however brief, account of the established facts connected with species, and
of the relation of the explanation of those facts offered by Mr. Darwin to the
theoretical views held by his predecessors and his contemporaries, and, above
all, to the requirements of scientific logic. We have ventured to point
out that it does not, as yet, satisfy all those requirements; but we do not
hesitate to assert that it is as superior to any preceding or contemporary hypothesis,
in the extent of observational and experimental basis on which it rests, in
its rigorously scientific method, and in its power of explaining biological
phænomena, as was the hypothesis of Copernicus to the speculations of
Ptolemy. But the planetary orbits turned out to be not quite circular after
all, and, grand as was the service Copernicus rendered to science, Kepler and
Newton had to come after him. What if the orbit of Darwinism should be a little
too circular? What if species should offer residual phænomena, here and
there, not explicable by natural selection? Twenty years hence naturalists may
be in a position to say whether this is, or is not, the case; but in either
event they will owe the author of "The Origin of Species" an immense debt of
gratitude. We should leave a very wrong impression on the reader's mind if we
permitted him to suppose that the value of that work depends wholly on the ultimate
justification of the theoretical views which it contains. On the contrary, if
they were disproved to-morrow, the book would still be the best of its kind the
most compendious statement of well-sifted facts bearing on the doctrine of species
that has ever appeared. The chapters on Variation, on the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection of the Geological
Record, on

Geographical Distribution, have not only no equals, but, so far as
our knowledge goes, no competitors, within the range of biological literature.
And viewed as a whole, we do not believe that, since the publication of Von
Baer's "Researches on Development," thirty years ago, any work has appeared
calculated to exert so large an influence, not only on the future of Biology,
but in extending the domination of Science over regions of thought into which
she has, as yet, hardly penetrated.